The casting of metal articles using sand molds and sand cores is well known in the art. A sand mold can be made from a mixture of sand and an organic binder by packing the mixture loosely or tightly around a pattern. The pattern is then removed, leaving a cavity in the sand that replicates the shape of the pattern. Once the organic binder is shape-stabilized by a curing technique, the cavity in the mold is filled with a molten metal by pouring the molten metal into the mold.
Sand mold cores can be made by placing a sand and binder mixture into a core box. There, the sand and binder mixture takes the shape of the cavity in the box, becomes hard, and is removed. After the mold is made, the core is then set in the mold. Molten metal is poured in the mold and fills the mold except where the sand core is present.
The binder materials used in making the sand molds, and sand cores can include inorganic binders, organic binders, and organometallic binders. Oraganometallic binders are uniquely suited for use as binders for sand molds and sand cores because they provide strength to the sand molds and sand cores at extremely low binder levels. Additionally, organometallic binders can be used to bind particles together to make shapes directly.
U.S. Pat. No. 5,884,688 discloses a method of fabricating shaped bodies such as negatives of parts to be made, as well as, shapes directly. The method comprises coating sand with liquid organic-metallic binder, forming a shape from said binder mixture, and hardening said binder mixture to form the shaped body. One organometallic binder is a polyureasilazane.
U.S. Pat. No. 5,552,466 discloses a method of producing an article with high temperature and thermal shock resistance comprising forming a blend of at least one lower viscosity silicone polymer. The blend is disclosed as being “cermitizable” at a temperature above about 1100° F. (590° C.). An article, formed in accordance with the patent, contains a layer of material formed from a silicone blend.